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AEA ST-1
by David 12 Mar '07

12 Mar '07

Greetings. I have an AEA ST-1 tracker unit that I would like to find drivers for DOS and Windows. I am using a 233MMX with windows 98 and running Nova for DOS which controls my 736R ok, but will not load the DOS driver that I have. Can anyone point me in the right direction or tell me what I am doing wrong besides running old programs. Thanks. Dave VA7DG

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Re: Sequencer
by joseph Murray 12 Mar '07

12 Mar '07

This issue might best include VOX and full duplex in a round table on HEO. Just in case Joe K0VTY ==================== On 12 Mar 2007 14:18:32 -0500 tosca005(a)umn.edu writes: > On Mar 12 2007, Edward Cole wrote: > > >At 05:15 AM 3/12/2007, Stargate wrote: > >>Is a sequencer needed when using a 160w switchable preamp from > ARR? > > > >Let's analyze this: > > > >You send a voltage to run the preamp. It needs voltage to switch > to > >Tx mode. When RF from your transmitter arrives it switches over to > > >bypass the preamp. I would guess if you turn off the power to the > > >unit, it can't operate correctly, so how is a sequencer going to > >help? I have not owned one of these units so not familiar with > their > >power wiring. If you have two 12 volt power contacts then you > might > >run the preamp separately from a sequencer. > > Sequencers don't have to only apply/remove DC power in a set > sequence. In > fact, in the general case, a sequencer has a series of switch > contacts that > are enabled in the proper order and disabled in the opposite order. > The > switch contacts could be configured as NO (normally open) or NC > (normally > closed). These can either provide and remove DC power, or short the > > pre-amp's own PTT circuit to ground to take it out of receive mode > (or, > depending on the model of preamp, maybe +12 is PTT instead of GND). > The > Down East Microwave sequencer has a DPDT relay for each of the > sequence > stages, so you get two independent NO and NC contact sets to play > with as > you wish. > > If (like the ARR models) the preamp has built-in bypass switching, > one > issue that remains is how quickly and completely the preamp gets > switched > out of the transmit path. If slow to switch, and/or if the isolation > is > insufficient, a spike of RF may still enter the very sensitive > preamp and > fry it. With a sequencer, you can (usually) select whatever > switching delay > is needed for the isolation relays to reach a fully switched > position, and > you also get to pick the isolation relays themselves, with attention > to > power dissipation and degree of isolation needed. I believe that ARR > says > that the built-in RF-sensing relay is good for up to 160 watts, but > a > sequencer with a separate isolation relay could basically allow you > to use > 1.5 kW, if you had an awfully darn good reason to use so much power, > ;) > that is. > > On my 144, 222, and 432 bands, I have an RF Concepts "brick" > amplifier with > an internal preamp and RF-sensed automatic switching. On 144 and > 432, these > are "soft keyed" (i.e. keyed by sensing RF). On 222, which is done > with a > transverter instead of directly out the back of my FT-847, I went to > the > effort to "hard key" the amp/preamp by using its PTT input (which I > had to > re-configure as PTT to GND instead of PTT to HI). Both "soft" and > "hard" > switching methods work OK, but on 144 and 432 it is best to briefly > pause > after keying the mic before you start talking, to insure that the PA > is > switched in, and when you unkey, you have to hope that the person on > the > other end pauses briefly before responding because it takes a > noticeable > amount of time for the amp/preamp relay to switch back to receive > mode. > (The delay is intentional, to prevent relay chattering.) On 222, > since the > radio, transverter, and external PA/preamp are all hard-switched by > their > own PTT signal, the send/receive cycle is much smoother, no excess > delays, > no chance of relay chattering if the loudness of your voice drops > low for a > moment, etc. So I definitely prefer the "hard keyed" method of > operation. > One of these days, I will get around to modifying the 144 and 432 > amps for > hard keying also... > > On 902, 1296, 2305, and 3456 MHz, my transverters were built with > split > Tx/Rx, which makes it simpler to connect a preamp (if needed) to the > Rx and > a power amp to the Tx, and of course you need a T/R coax relay > external to > the transverter. So far, because my PA's on these bands are low > power, I > hard-key the T/R relay but it is not sequenced -- radio PTT = > transverter > PTT = T/R relay PTT, all at the "same" time. When I move up to the > high-power class of operation, I will install a sequencer on each. > We have > local folks here who have had the experience I am trying to avoid, > namely > simultaneous switching works ok at low power, but add in some REAL > output > power and things fry if not sequenced. These bands have PA's of > 40-120 > watts waiting to be integrated. (This is for terrestrial work, not > satellites, by the way, as you can probably figure from the high > powers and > non-satellite bands/sub-bands mentioned...) > > 73 de W0JT > AMSAT-NA LM#2292 > _______________________________________________ > Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the > author. > Not an AMSAT-NA member? Join now to support the amateur satellite > program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > >

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Timonium
by MARTHA SARAGOVITZ 12 Mar '07

12 Mar '07

It now appears we have NO ONE to handle Timonium on March 31st and April 1st. Would someone PLEASE volunteer to "man" the booth on Saturday? 73- Martha

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Fw: Dayton
by MARTHA SARAGOVITZ 12 Mar '07

12 Mar '07

----- Original Message ----- From: "MARTHA SARAGOVITZ" <amsat(a)verizon.net> Subject: Dayton OK - I have 30 non-smoking rooms- 10 singles, 20 doubles for Dayton. We are staying at the Fairborn Hampton Inn. To hold a room, you need to call me (301-589-6062) with: 1. dates of room nights 2. daytime phone number 3. charge card number Remember - If you snooze, you lose! 73- Martha

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Hy-gain DB218SAT Oscar antenna experience?
by Alan P. Biddle 12 Mar '07

12 Mar '07

Hi, I see that Hy-Gain/MFJ still at least lists the old Hy-gain Oscar antennas: http://www.hy-gain.com/products.php?catid=7 Like the old Cushcraft AOP-1, they were a bit short on gain for P3 birds, but otherwise seemed to be a relatively simple way and reasonably priced way to get coverage with switchable circularity. Certainly good enough for current LEOs and possibly the newer P3 birds. I was asked by someone just getting started about them, and wondered if anyone had practical experience? We have discussed the many alternatives, so I would rather keep to just this antenna. Alan

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Fixed Elevation LEO Orbit figure
by Robert Bruninga 12 Mar '07

12 Mar '07

To help clarify the elevation discussion, I have added a drawing of a LEO orbit passes relative to a station's antenna to the web page: http://www.ew.usna.edu/~bruninga/rotator1.html It clearly shows how most satellite times are below 30 deg, and 10 dB more gain is needed to work satellites at those near horizon angles compared to above 50 degrees where satellites are 10 dB closer and spend less than 5% of their time.\ I think the visualization helps a lot in these discussions and shows how only a simple TV rotator and small beam is needed for all LEO's.. By the way, I am not pushing the rotator interface indicated in the web page above. That web page is over 6 years old, and I only keep it on-line to encourage all other Satellite Tracking programs to add the same simple 2-bit TV rotator interface that would make LEO satellite operation so simple and innexpensive, that it would help newcommers join the satellite operations at minimal cost. There just is no need for a "typical OSCAR array" for LEO operation. We do ourselves a disservice by only having tracking programs that can only control $1000 rotators when a simple $70 one will do perfectly for LEO's. Bob, WB4APR

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(no subject)
by Patrick McGrane 11 Mar '07

11 Mar '07

I noticed some spots about satellite beams for fm birds. After 2 years of trying different anrtennas etc, I now have my ideal setup. I tried 3 different homebrew beams. I learned that for a fixed elevation on azimuth rotator, the optimum beam was 7 elements at 10 degrees elevation with a DELTA match on the driven element. I have great reception using a hamtronics preamp (lnk-450) on the shack end of a 15 foot run of 9913 coax. The reception is good to great from just a few degrees above the horizon up to the zenith or overhead. I tried 8 elements with a gamma match but was too sharp with little overhead gain. I tried a 7x7 cross yagi fixed at 20 dgrees with minimal success. The horizontally polarized 7 element delta match outperforms it vastly. I'm guessing the delta match helps with the higher angles. ( Delta match looks like a triangle at the center of the driven element.) Consult the antenna book by ARRL or search for information. Photo of antennas at: http://members.aceweb.com/n2oeq Hope this helps someone. 73, pat

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Re: 1.2ghz useful??
by Terry Carrell 11 Mar '07

11 Mar '07

Uplink on 1.2GHz [23cm band in the (Amateur) Satellite Service] (FM & Linear Modes) will be used by KiwiSAT which is planned for launch late 2008 early 2009 - finances permitting. See http://www.kiwisat.org [Note: The uplink frequency is not 1.298 Ghz as some might suggest but in the satellite segment more correctly referred to as 1.268 GHz] Terry, ZL3QL. ----- Original Message ----- From: "Stargate" <stargatesg1(a)verizon.net> To: "Amsat-Bb" <amsat-bb(a)amsat.org> Sent: Sunday, March 11, 2007 3:32 PM Subject: [amsat-bb] 1.2ghz useful?? > Is 1.2ghz (uplink or downlink) planned for any of the upcoming sat's? > > Thanks, > RoD > KD0XX > > A good friend will come and bail you out of jail, > A TRUE friend will be sitting next to you saying..... > > > "DAMN THAT WAS FUN" > _______________________________________________ > Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.446 / Virus Database: 268.18.8/717 - Release Date: 10/03/2007 > 2:25 p.m. > >

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1.2ghz useful
by Stargate 11 Mar '07

11 Mar '07

Well, I guess I should have been a bit more accurate. Is 1296mhz going to be used in any future satellites or will it be 1268MHZ. The reason for asking is I have the opportunity to purchase a DEMI 1296-144 transverter. P.S. I need an answer soon please:-) Thanks, RoD KD0XX A good friend will come and bail you out of jail, A TRUE friend will be sitting next to you saying..... "DAMN THAT WAS FUN"

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Grade 10 Learner from Kimberley will speak from space
by Trevor 11 Mar '07

11 Mar '07

It case anyone hasn't heard the latest on SumbandilaSat see http://www.southgatearc.org/news/march2007/sumbandilasat.htm It's good to see that SA AMSAT are actively involving young people in the project. 73 Trevor M5AKA --------------- Daily Amateur Radio RSS News: http://www.southgatearc.org/ Email your news items to: editor at southgatearc.org News On Your Website: http://www.southgatearc.org/rss/index.htm News On Your PC: http://www.southgatearc.org/rss/newsreader.htm Upload Your News: http://www.southgatearc.org/news/your_news.htm --------------- ___________________________________________________________ To help you stay safe and secure online, we've developed the all new Yahoo! Security Centre. http://uk.security.yahoo.com

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